The present invention relates to sliding door and window closing mechanisms. In recent years, sliding doors and windows have come into great usage in hotels, homes and office buildings. At the same time, the cost of the energy needed to heat and/or cool such buildings has increased dramatically. Because large amounts of heated or cooled air may escape from a sliding door or window which has been left open, there is a great need for a simple automatic door and window closing mechanism.
Various door closing mechanisms are known in the prior art including U.S. Pat. Nos. 4,649,598, 4,003,102, 3,334,444, 4,126,912, 4,004,372, 4,301,623, and 3,978,617. Of these, No. 4,649,598 (Kiney) and No. 3,334,444 (Hargrove) appear most pertinent. Both Kinsey and Hargrove disclose door closing mechanisms utilizing a cylindrical tube having a weight disposed therein which is connected to a cable which passes across a pulley which is attached to an anchor in the door jamb. Each of these door closing mechanisms utilizes a port or valve means at the bottom of the cylindrical tube to control the flow of air passing therethrough. In addition, the Kinsey door closer includes a valve means built into the top part of the weight so as to control the flow of air at the top of the weight, as well as the bottom of the tube. The specific function of the Kinsey valve is to allow air to escape when the door is closed quickly.
Hargrove discloses an air regulation valve at the bottom of the cylinder in which the weight is disposed. The weight itself is very close to the same diameter as the tube. By adjusting the valve at the bottom of the tube, the speed at which the weight drops within the cylinder may be controlled.
Both Kinsey and Hargrove suffer from numerous drawbacks. Most notably, neither provide for an efficient control of the column of air disposed within the tube below the weight and above the port means. Although Kinsey describes the pneumatic seal, a feature notably absent from Hagrove, this seal is part of the valve means at the top (not bottom) of the weight. This particular valve is virtually unnecessary and has been eliminated from the present invention. Moreover, a pneumatic seal is provided in the present invention as a modified O-ring around the weight intermediate its ends, at a location near the bottom of the weight itself.
It is therefore an object of the present invention to provide an automatic door and/or window closing device which includes a weight disposed within a cylindrical tube connected at the top to a cabling means which passes across a pulley and is mounted to the door header. At the bottom of the weight a pneumatic seal is provided which prevents the flow of air from passing from below the weight into the tube above it. A port means having a valve attached thereto is provided at the bottom of the tube to provide adjustable restriction on the air passing therethrough.